Nowadays, widely used are vehicles carrying a rotary electric machine in addition to or instead of an internal-combustion engine as a drive source.
Examples of the vehicles include what is called hybrid electric vehicles and electric vehicles.
JP2014-23338A disclosed an invention of a rotary electric machine system having: a permanent magnet motor (rotary electric machine) having a rotor equipped with permanent magnets, a stator facing the outer circumferential surface of the rotor with a gap therebetween, and a stator coil by which each tooth of the stator is wound; and a control unit configured to execute drive control of the rotary electric machine.
In the rotary electric machine system of JP2014-23338A, the rotary electric machine is driven by controlling a d-axis current component and a q-axis current component on the basis of vector control. When the rotary electric machine is driven, the d-axis current component and the q-axis current component are calculated on the basis of an operation state of the rotary electric machine and a magnet temperature in the permanent magnet motor is calculated. When the calculated magnet temperature is lower than a predetermined value, the d-axis current component is added so as to more magnetize each magnet, and the rotary electric machine is operated.
According to the rotary electric machine system of JP2014-23338A, the magnet temperature can be rapidly increased and permanent demagnetization of each magnet can be prevented without causing any torque pulsation and noise.